This Core has two major goals or aims that are essential for the success of all four Projects and the Program itself. These two major goals are to obtain and maintain established mouse lines that are needed for the progress of Programmatic use, to provide a facility for the generation, propagation and distribution of viral vectors for analysis of coronary vessel development. The Core will also provide Core B, the Morphology and Imaging Core, materials for immunochemical analysis in the generation of our "Index of Gene Expression in the Developing Coronary System." There are two components of the Core housed at Vanderbilt and Cornell Universities. This arrangement takes advantage of the expertise, facilities and equipment already in place and negates major changes in personal, training and logistics. This Core is essential for the maintaining the integrated nature of all four Projects of the Program and provides the most efficient and cost effective use of resources.